An effective pair potential for dipolar fluids

Abstract

The possibility of representing the orientational correlations in a dipolar fluid by an effective pair potential, U _eff(r), depending only on the separation r, is considered. U _eff(r) is obtained from the two-particle orientational partition function by series expansion and direct numerical integration methods for a wide range of interaction strengths. Free energies are obtained for the dipolar hard sphere fluid by use of the GvdW theory of simple fluids and compared with Monte Carlo simulation results. The coexistence curve is also obtained and compared with Monte Carlo, Padé and MSA results. The critical temperature is overestimated by about 30 per cent but the critical volume agrees well with the simulation estimate.